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To: pgus-general@postgresql.org
Subject: journaled FS and and WAL
Date: Fri, 14 Oct 2016 13:22:55 +0200
Message-ID: <5800C00F.4030208@gmail.com> (raw)
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Hi,
two question related to the WAL.
1) I read in the doc that journaled FS is not important as WAL is
journaling itself. But who garantees that the WAL is written correctly?
I know that it's sequential and a partial update of WAL can be discarded
after a restart. But am I sure that without a journaled FS, if there is
a crash during the WAL update, nothing already updated in the WAL before
my commit can get corrupted?
2) Let's suppose that I have one database, one table of 100000 rows,
each 256 bytes. Now, in a single SQL commit, I update row 10, row 30000
and row 80000. How much should I expect the WAL increase by? (supposing
no WAL segments will be deleted). I could guess 8192x3 but I'm not sure
Regards
Pupillo
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Subject: Re: journaled FS and and WAL
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